Foreign key to base table with rows in inherited tables

I've declared a foreign key in table FileId referencing the primary key in
Datafile. Datafile in itself does'nt have any rows, but Reservationfile,
inheriting from Datafile has.

I can't insert a row in FileId because no row is found in Datafile: this is
not what I expected.

I've tried suffixing Datafile with an asterisk (even though that shouldn't
be necessary in 7.1), but that's not valid syntax.

I'm running 7.1.release4 on Debian Woody.

Table definitions for clarity:

-- Has no rows of its own
declare Datafile (
datafileNr not null primary key
);
-- This one has rows
declare Reservationfile (
)
inherits(Datafile)
;
declare FileId (
datafileNr not null
references Datafile
);